The invention relates to marine coatings having anti-corrosion and anti-fouling properties.
Marine fouling, which results from the growth of marine organisms of vegetal or animal origin on the surface of immersed bodies, may have very detrimental consequences, such as an increased weight of the immersed structures and an accelerated corrosion. Marine fouling also increases the roughness of the ship hulls, and thus their resistance to displacement in water, which increases their fuel consumption in a proportion which may reach, for example, 40%.
An efficient manner to fight against marine fouling consists of maintaining a toxic material at an effective concentration and in continuous and homogeneous manner on the surface to be protected. The anti-fouling paints which have been employed up to now resort to this technique and operate by continuous release of a toxic agent--generally containing copper or tin--soluble in water. A number of methods have been developed, in order to control more efficiently the rate of liberation of the toxic agent in the aqueous medium; however, irrespective of their improvements, these anti fouling paints suffer from two major disadvantages:
on the one hand, the anti-fouling effect is obtained within a relatively short period, which requires frequent inoperative periods of the ships for cleaning of their hull; and PA1 on the other hand, the relatively high amounts of toxic agent required result in a pollution of the environmental nature. PA1 at least one sub-layer of chlorinated natural rubber (anti-corrosion layer) and PA1 a superficial layer of at least one polyamide (anti-fouling layer). PA1 fatty polyamides resulting from the reaction of a diamine with dimerized unsaturated fatty acids; PA1 copolyamides such as, for example, a 6/6.6 copolyamide based on adipic acid/hexamethylene diamine and caprolactame, a 6/6.6/6.10 copolyamide based on adipic acid/hexamethylene diamine, decanedioic acid/hexamethylene diamine and caprolactame, a copolyamide of hexamethylene diamine/adipic acid, p.p'-diamino dicyclohexylmethane/adipic acid and caprolactame, a ternary 6/6.6/12 copolyamide of caprolactame, adipic acid/hexamethylene diamine and lauryllactame or a ternary 6/6.12/12 copolyamide of caprolactame, dodecanedioic acid/hexamethylene diamine and lauryllactame; PA1 grafted or sequenced copolymers based on polyamides or copolyamides and on sequences or grafts based on polyethers, polly-epoxy or polyesters. PA1 the esters of aliphatic monoalcohols, diols or amino-alcohols with carboxylic acids having a vinylic unsaturation, such as, for example, methyl, ethyl, propyl, butyl, 2-hydroxy ethyl or diethylaminoethyl acrylates and methacrylates, PA1 the amides with vinyl groups such as, for example, acrylamide, methacrylamide, N,N-dimethylaminopropyl methacrylamide.